Effect of Corrosives and Partial Burn on The Insects’ Succession and Decay of Buried Cadaver in Different Types of Soil

Forensic entomology is a growing field of study. Determination of the postmortem interval (PMI) is one of the most common tasks of the forensic entomologist. The objective of this study was to determine the difference in decomposition and faunal succession between control rats and rats treated by corrosives or partial burn; which were buried in different types of soil (dust or sand). Twenty-seven healthy adult rats (180 ± 30 g) were randomly divided into three groups; 9 rats each. Each group was subdivided into three subgroups; Group I served as control group, Group Ia (killed by decapitation and left uncovered), Group Ib (buried in dust), Group Ic (buried in sand). Group II included partially burnt rats after killing by decapitation (IIa uncovered, IIb buried in dust and IIc buried in sand). Group III burnt by using sulfuric acid after killing by decapitation (IIIa uncovered, IIIb buried in dust and IIIc buried in sand). The experiment was conducted in winter months as the temperature in Upper Egypt (Assiut) varies from morning to night. The first insect arrival time; as well as the species of insects and its relation to the stages of decomposition were determined. The presence of insects was checked at regular intervals during the period of experiment. The use of these different types of concealing methods and different soils in burial did not only affect the time of first insects' arrival but also the species of insects and stage of decomposition. In uncovered control rats (GIa), the first insect seen was Sarcophaga sp., with highly significant delay in uncovered rats concealed with corrosives. Wohlfahrtia sp. was the first species appeared in uncovered rat concealed with corrosives. There was highly significant rapid appearance of insects in partially burnt groups and highly significant delayed appearance of insects in groups concealed with corrosives. Highly significant appearance of insects in groups buried in sand was noticed compared with the same control group while there was significant delay in appearance of insects in groups buried in dust.  Distinct delay in decompostion stages was observed in those concealed with corrosives and buried in dust. It could be concluded that the combination of different methods of concealing the cadaver and burning was very effective in changing the post mortem interval, successions of insects and their species upon the cadaver.